using System.Speech versus using Microsoft.Speech

Hello, I have been writing speech recognition and synthesis programs using SharpDevelop and C#.  I'm using the System.Speech namespace. Everything has been working ok so far, but recently I found the SRGS system (Speech Recognition Grammar Specification) used by Microsoft.  However, when I try to use those methods I get an error message that they don't exist.

I'm using the System.Speech namespace.  But Microsoft refers to theirs as Microsoft.Speech.   Can I add Microsoft.Speech to the SharpDevelop references?  And if so, how do I go about doing that. They don't currently show up in the Add References options.

Thanks.